HDRI and Noise

[DartFrog]

I have an interior scene that renders fine with a default gray color in the environment. It cleans up quickly. It looks much better overall if I put in an HDRI in the env spot, but it takes about 10x longer to clean up, if it even cleans up. Is there a trick to using HDRI files as a lighting source?

I tried applying it directly to a sphere and increased the samples to 200, not really any better. I switched to PMC from PT and it's better, over time, but still not nearly as quick as when I'm not lighting with HDRI. Does anybody have any advice?

[profbetis]

Did you enable Importance Sampling in your Texture Environment settings?

[DartFrog]

Yeah. It was on by default anyway. I also tried making a sphere with the HDRI texture pointed inward toward the scene and raised samples to 200, still crap. I gave up. I even threw portals in the non-glass windows to help direct light but I just don't think interiors are lightable from HDRIs, not yet anyway.

[profbetis]

That is a shame. One thing you might try too is adding octane lights or mesh lights in your windows (if octane lights, uncheck visible). This should help fill your room with lights that samples better. It's not ideal but you might be able to tweak it to get close to what you need.

[mbetke]

Can you show us some screenshots?

[DartFrog]

When I'm back in that scene I'll try to get a screenshot. Regarding adding mesh lights, @profbetis, normal lights aren't an issue. It was just lighting with hdri that was the problem. Putting hdri lights in the windows might help... but the light falloff would be all messed up, too severe.

[azen]

Hi,

There are a number of possible causes for this issue. First all, what are the specs for your machine? This will help to eliminate possible hardware-related issues.

Otherwise, I would be happy to look over your scene directly and provide you with a working solution. If you are unable to provide the scene for any reason, providing screenshots to look over would also be a great starting point.

Please let me know how you would like to proceed.

Cheers,

Azen
OctaneRender Team

[mbetke]

My guess is he set wrong Gamma for the HDRI or exposure settings. Some HDR need to be very reduced in those values. Like the Gruthie HDR maps.